Illuminating system with gas discharge lamp used at low and high power levels

ABSTRACT

The disclosure embraces an electric system including a gas discharge arc lamp construction of a character particularly for use in the graphic arts field and a transformer power circuit for a gas discharge arc lamp wherein an increased voltage for momentarily effecting gas ionization and establishment of the arc is attained through the summation of a peak charge of applied alternating current voltage of a capacitor occurring during onehalf cycle applied directly to the lamp in series with the applied voltage from the transformer during the alternate half cycle and thereafter shorting out the capacitor for applying the normal voltage of the transformer to the arc lamp for normal operation.

United States Patent Kiefer et al.

ILLUMINATING SYSTEM WITH GAS DISCHARGE LAMP USED AT LOW AND HIGH POWER LEVELS Inventors: Edward J. Kiefer; Dale W. Rogers,

both of Toledo, Ohio Assigne e: Holopllane Company Incorporated,

New York, N.Y.

Filed: July 26, 1973 Appl. No.: 383,034

Related US. Application Data Division of Ser. No. 166,034, July 26, 1971, Pat. No. 3,760,226.

References Cited UNITED STATES PATENTS 12/1959 Caine et al 95/57 X June 10, 1975 Perner et a1. 355/71 Weishsmantel 44 355/71 X [57] ABSTRACT The disclosure embraces an electric system including a gas discharge are lamp constniction of a character particularly for use in the graphic arts field and a transformer power circuit for a gas discharge are lamp wherein an increased voltage for momentarily effecting gas ionization and establishment of the are is attained through the summation of a peak charge of applied alternating current voltage of a capacitor occurring during one-half cycle applied directly to the lamp in series withthe applied voltage from the transformer during the alternate half cycle and thereafter shorting out the capacitor for applying the normal voltage of the transformer to the arc lamp for normal operation,

4 Claims, 6 Drawing Figures A! MC M0.

K4 Md M6. W (at 4 PATENTEDJUMIO I975 SHEET 1 3888583 ILLUMINATING SYSTEM WITH GAS DISCHARGE LAMP USED AT LOW AND HIGH POWER LEVELS This is a division of application Ser. No. l66.034. filed July 26, 1971. now issued into U.S. Pat. No. 3.760.226.

This invention relates to an electric system involving a gas discharge are lamp of a character particularly for use in the graphic arts field. the lamp embodying a power circuit for the gas discharge are lamp utilizing the voltage of a transformer secondary for normal are operation and wherein an increased voltage is established through capacitor means sufficient to effect establishment of the are and wherein alternating current is employed for normal lamp operation.

Lamps of the character heretofore used in the graphic arts field have embodied special ignition transformers and devices to provide high voltage alternating current for ignition of a gas discharge are lamp and thereafter a reduced voltage direct current utilized for normal lamp operation.

In the use ofa gas discharge lamp in the graphic arts field it has been a practice to de-energize the gas discharge lamp after each exposure operation. In making successive short exposures, considerable time is involved in bringing the gas discharge lamp to an operating temperature and cooling the lamp preparatory to a subsequent exposure operation.

The present invention embraces a lamp construction embodying a gas discharge are lamp and a power circuit or electric system therefor wherein alternating current of high voltage is provided for establishment or ignition of the gas discharge lamp and alternating current voltage of a transformer utilized for normal operation of the lamp, and the power for the lamp reduced during standby periods whereby de-energization of the lamp between successive periods of normal operation of the lamp may be avoided.

An object of the invention embraces a power system or circuit for a gas discharge are lamp wherein a high alternating current starting voltage for igniting the lamp is attained through the summation of the voltage ofa half cycle of applied alternating current ofa transformer with the voltage of a capacitor charged to the peak of applied alternating current voltage occurring during the alternate half cycle and whereby the lamp upon ignition operates at a normal alternating current voltage from the transformer.

Another object of the invention resides in the provision of a lamp structure wherein the lamp enclosure is provided with a shutter movable to light exposing and light obstructing positions and a circuit system for a shutter drive motor arranged to provide dynamic electric breaking of the motor for preventing over-travel of the shutter in its movements from one position to the other.

Another object of the invention resides in a lamp construction embodying a gas discharge are lamp and a power circuit therefor for operating the lamp at a high power level and for operating the lamp at a low power standby level.

Another object of the invention is the provision of a lamp structure including a gas discharge are lamp and reflector means therefor disposed in a housing and multiple blower means in the housing wherein one blower is effective for venting the lamp housing and another blower supplementing the first blower rendered opera- 2 tive during high power operation of the lamp to effectively cool the arc lamp.

Another object of the invention embraces an electric system or power circuit wherein the summation of alternating current voltage from a transformer and the peak voltage of a capacitor is employed for ignition of a gas discharge lamp and alternating current voltage from the same transformer utilized for normal operation of the lamp in conjunction with control means for continued energization of the lamp at standby low power operation whereby the lamp is maintained at an elevated temperature during low power operation in readiness for high power operation thereby eliminating warm up periods for the lamp.

Further objects and advantages are within the scope of this invention such as relate to the arrangement. operation and function of the related elements of the structure, to various details of construction and to combinations of parts, elements per se, and to economics of manufacture and numerous other features as will be apparent from a consideration of the specification and drawing ofa form of the invention, which may be preferred, in which:

FIG. 1 is a side elevational view, partly insection, of a lamp construction embodying a gas discharge are lamp;

FIG. 2 is a front elevational view of the lamp construction shown in FIG. 1;

FIG. 3 is a rear elevational view of the lamp construction;

FIG. 4 is a rear elevational view of the lamp construction with the rear cover removed;

FIG. 5 is a semischematic view ofa shutter or curtain for the exposure opening of the lamp housing, and

FIG. 6 is a schematic diagram of the power circuit of the invention for the ignition and operation of the gas discharge are lamp.

While the gas discharge are lamp construction and power circuit ofthe invention have particular utility for lighting exposure purposes in the graphic arts field. it is to be understood that the arc lamp construction and power circuit therefor may be used wherever the same may be found to have utility.

Referring to the drawings, the arc lamp construction illustrated is of a character particularly usable in the photocopy and graphic arts field. The lamp construction is inclusive of a base 20 provided with caster wheels 21 and having a hollow boss which receives the lower end of an upwardly extending tubular support member 22 secured in place by a bolt 23. Teleseoped into the tubular member 22 is a second tubular member 24, at the upper end of which is mounted a bracket 26 supporting a rectangular lamp housing 28 secured to the bracket by screws 27. The housing 28 is preferably fashioned of sheet metal and is provided with a removable rear cover or closure member 29.

Surrounding the tubular support member 24 is a circular clamp 30 which is split as at 31 and is equipped with a clamp screw 32. As shown in FIG. I, the clamp member provides an adjustable abutment engageable with the upper end of the tubular member 22. By manipulating the clamping screw 32, the position of the support tube 24 may be adjusted relative to the tube 22 for varying the height of the lamp housing 28 with respect to the base 20. A second housing 34. mounted upon the base 20, encloses a transformer and other electrical components of the system.

A housing or casing 36 secured to an exterior wall of the lamp housing 28 encloses a timing means or timer for the lamp. As shown in FIG. 2, the timer housing 36 supports an adjustable timing member 38 which cooperates with indicia 39 indicating minutes. the member 38 being adjustable to vary the operational periods of the lamp. Disposed within the lamp housing 28 are bus bars or supports 42 connected with a current supply. Each bus bar 42 is equipped with a clip or member 44 for supporting a gas discharge lamp or lamp bulb 46 of elongated shape, the clips engaging end regions of the lamp envelope.

As an example, the hollow region of the lamp envelope may be approximately four inches or more in length providing an arc of desired length. The bulb or lamp 46 is of a conventional type containing mercury and preferably a metal additive such as a halide to concentrate the radiant energy in a desired spectral range. Disposed in the housing 28 is a reflector 48 supported by frame members 50, shown in FIG. 4.

The reflector 48 is of curved confguration such as a partial spherical or ellipsoidal shape for reflecting rays of light from the lamp 46 forwardly through a glazed window 52 shown in FIG. 1. A supplemental light reflecting or guiding means 54 fashioned of sheet metal is disposed in the housing forwardly of the reflector 48, the reflector 54 being of generally frusto-pyramidal shape provided by four converging walls 56, shown in FIGS. 1 and 2.

A casing or supplemental housing 58, illustrated in FIGS. l and 4, disposed in the lamp housing 28 encloses electrical control components in addition to those contained within the base housing 34. The power supply is connected with a transformer disposed in the housing 34 as well as other components of the power circuit, the circuit connections for the components disposed in the housing 58 being contained within a sheath or cable 60, shown in FIG. 1, connected by a fitting 61 with a housing 58, a slot 62 in the cover member 29 accommodating the fitting 61. The timer contained within the housing 36 is connected with components in the housing 34 by connections contained within a sheath 64 shown in FIG. 1.

Means is provided in the lamp housing 28 for ventilating the lamp housing and for directing a stream of air into the region of the gas discharge lamp 46 for cooling the lamp when the lamp is in high power operation. The housing ventilating means includes a blower or fan 66 driven by a motor 81 preferably supported in the housing 28 adjacent the rear cover member 29. The rear cover member 29 is provided with a screened opening 68 for admitting air into the lamp housing 28 under the influence of the rotating fan or blower 66. The side walls of the housing 28 are provided with louvers 70, shown in broken lines in FIG. I, to facilitate circulation of air through the lamp housing.

A second blower or blower means 72 is disposed in the lamp housing rearwardly of the reflector 48, the air exit tube 74 of the blower being aligned with an opening 76 at the central region of the reflector 48 whereby a stream of air from the blower is delivered through the opening 76 to the region of the gas discharge lamp 46. The opening 76 is provided with a grid 78 to effect diffusion of the air delivered toward the lamp 46. The blower 72 is driven by a motor B2 which is energized as hereinafter described through the timer means contained in the housing 36, the blower 72 being operated 4 only when the gas discharge lamp 46 is operating under full power.

A relatively movable curtain or shutter means is provided for obstructing passage of light from the are except when an exposure is made for a graphic reproduction. The arrangement is inclusive of a flexible impervious curtain, shutter or light obstructing means 80 illustrated in FIGS. 1 and 5, the curtain and associated components being shown in detail in FIG. 5. Disposed at an upper frontal region within the housing 28 is a horizontal roll 82 having tenon portions 83 journaled in openings in the side walls of the lamp housing 28.

Secured to the lower end of the curtain or shutter 80 is a transversely extending bar 85, a second bar 86 being secured to the other end of the curtain, the bars being movable with the curtain. .lournally supported at the lower frontal corners of the housing 28 are pulleys 88, a second set of pulleys 90, shown in FIG. 5, being disposed adjacent the lower mid-region of the housing. Secured to the respective ends of the bar are cables 92, each cable being engaged with pulleys 88 and 90 in the manner shown in FIG. 5. The ends of the cables adjacent the pulleys 90 are secured to a clip or connector 94.

Connected to the respective ends of the bar 86 is a cable 96, the cable 96 being connected at its midregion with a clip or connector 98. Joined with the connectors 94 and 98 are the end regions of a flexible member, cable or tape I00 which, as shown in FIG. 5, is engaged with pulleys 102 and 103 disposed at the central upper and lower regions in the housing adjacent the rear cover 29. Mounted upon a support plate or member 105 mounted within the lamp housing 28 is a motor B3 of a conventional reversible type, the shaft of which is equipped with a drive roll I07. Idler or tape guiding rolls 109 are journally mounted for rotation on the plate 105.

As particularly shown in FIG. 5, the tape or member 100 is engaged with the idler rolls 109 and extends partially around the drive roll 107. A roll Ill, mounted on an arm or lever 112 pivoted on the plate 105, is biased into engagement with the tape 100 at the region of the drive roll 107 by means ofa contractile spring 115 connected to an end of the lever I12 and the plate 105. The contractile spring 115 exerts pressure on the roll 111 to assure a drive connection between the driving roll I07 and the tape 100. The light obstructing means or curtain 80 is shown in open position in FIGS. 1 and 5, that is, in a position where light from the lamp 46 passes unobstructed through the glass 52.

With particular reference to FIG. 5, it will be apparent that upon rotation of the motor 83 in the proper direction, the tape 100 will be moved in a direction to move the curtain 80 into a position obstructing the passage of light from the lamp housing. The movement of the curtain 80 to light obstructing position is determined by a limit switch S3, and the movement of the curtain 80 to open position is determined by limit switch S4. The use of the flexible tape 100 facilitates opening and closing movements of the curtain or light obstructing means 80 without engaging or impinging the bars 85 and 86 against fixed abutments.

The controls for the motor B3 and the controls for the other motors and components are illustrated schematically in FIG. 6. The operation of the various components will be explained in describing the circuitry illustrated in FIG. 6. The circuit includes a transformer Tl, the transformer being supplied with alternating current from power lines L1 and L2 through a master switch S1. The timer motor is illustrated at B4.

In order initiate ignition of and form an arc in the gas discharge lamp 46 and prepare the components for automatic lamp operation, the switch S2 is moved to closed position. The switch S1 is closed supplying alternating current, for example. 60 cycle alternating current of 250 volts, to the primary 118 of the transformer T1. The transformer provides alternating current of 1 l5 volts to the control circuit through the circuit breaker CBl. As an example, a voltage of about 350 volts in the secondary 120 of the transformer is supplied to the circuit of the gas discharge lamp 46 through a capacitor C], but it is to be understood that a transformer providing a higher or lower secondary voltage may be employed depending upon the characteristics of the gas discharge lamp.

The secondary voltage of the transformer is sensed by relay Kl or other switch means through a resistor R2, and the relay or switch means K1 is energized. Energization of the relay Kl opens contacts 5 and 8 of relay Kl preventing operation of relay or switch means K3. Contacts 1 and 3 of relay K1 are closed and such action connects the diodes CR1 and CR2 in series with a fuse F across the gas discharge are lamp 46 and in series with the capacitor C1 across the secondary 120 of the transformer T1. The closing of contacts 1 and 3 of the relay Kl establishes a shunt of the relay or switch K2 protecting the relay K2 from high voltage. A capacitor C3 is disposed in parallel with the diodes CR1 and CR2 in order to prevent damage to the diodes in event of an excessive voltage surge.

Through the circuitry above described, a high voltage is developed, for ex ample, 990 volts in the circuit of the gas discharge are lamp 46 which is sufficient to effect current flow through the lamp 46 and ignite or energize the lamp. During one-half cycle of the applied alternating current voltage from the secondary 120 of the transformer T1, the capacitor C l is charged to the peak ofthe applied alternating current voltage, viz. 495 volts by current conduction through the diodes CR] and CR2.

During the alternate half cycle, the diodes CR1 and CR2 do not conduct current, and the peak voltage of the charge of the capacitor C l is applied directly to the arc lamp 46 in series with the alternate half cycle of the applied voltage from the secondary 120 of the transformer Tl. Thus, the peak voltage applied to the gas discharge are lamp 46 is the sum of the applied peak voltage of the transformer secondary I and the voltage of the charged capacitor CI, for example. the summation of the peak voltages being approximately 990 volts. This peak voltage of 990 volts is amply sufficient to establish current flow through the gas discharge lamp 46 and thereby ignite the lamp. This action is repeated every other half cycle until the lamp 46 is ignited. lt is to be understood that gas discharge lamps may be employed requiring transformers of different secondary voltages.

After current flow is established by the high voltage through the gas discharge lamp. the voltage across the lamp 46 falls to a low value by reason of the capacitor Cl and the characteristics of the transformer T1. The voltage falls to a sufficiently low value as to de-energize the relay Kl. De-energization of the relay Kl opens contacts 1 and 3 of the relay K! which connects the 6 voltage sensing relay K2 in the circuit in series with the diodes CR1 and CR2.

Contacts 5 and 8 of relay Kl close, this action energizing relay K3 through the switch 82A and contacts 1 and 4 of relay K2. Energizing the relay K3 shorts out the capacitor C1 to place the arc lamp 46 directly across the secondary 120 of the transformer T1. Relay K3 has two sets of contacts K3 1 and 2 and K3 3 and 4. Contacts 1 and 2 of relay K3 close first, placing the resistor R] in parallel with the capacitor CI. in a very short period of time, contacts 3 and 4 of relay K3 close, this action shorting out the capacitor C1. The momen tary preclosing of contacts 1 and 2 of relay K3 reduces arcing of contacts 3 and 4 of the relay K3.

The motor Bl, driving the housing ventilating fan 66, is energized continuously when the main switch 8] is in closed position. The motor B3, for operating the shutter or curtain 80, is energized through contacts 1 and 4 of the relay or switch means K4 and the normally closed contacts (N.C.) of limit switch S3 to close the shutter or curtain 80, this is, to move the shutter or curtain to the position covering the open end of the reflector 54.

When the shutter is closed, the motor B3 is deenergized and dynamic electric braking is applied to the fields of the motor B3 by the opening of the normally closed (N.C.) contacts of the switch S3 and the closing of the normally open (N.O.) contacts of the switch S3 to reduce overtravel of the shutter or curtain to a minimum.

As the arc lamp 46 warms up, the voltage across the arc lamp increases. When the voltage reaches a predetermined value, which indicates that the lamp 46 is sufficiently warmed up, relay K2 is energized through the diodes CR1 and CR2 and the resistor R3. A capacitor C2 is provided for the purpose of preventing relay chatter of the relay contacts. A resistor R4 is disposed across the capacitor C2 for preventing a high voltage occurring across the capacitor C2 in event that the coil of relay K2 is open.

As relay K2 is energized, contacts 4 and l of relay K2 open and contacts 1 and 3 of relay K2 close. This contact action de-energizes relay K3. The contacts I, 2 and 3, 4 of relay K3 open, placing the capacitor C 1 in series with the arc lamp 46 and reducing the power to the lamp 46 to a standby level. Contacts 8 and 6 of relay K2 close. The foregoing operations occur in warming up the gas discharge lamp 46 and such actions require a period of about one minute, the lamp now being in standby operation in readiness for automatic operation in making exposures or reproductions which require high power for the lamp.

The length of time of an exposure is controlled by a manually adjustable timer motor 84 contained within the timer housing 36. The timer arrangement is shown schematically in FIG. 6 and includes a push button switch 122, a timer switch 124 and a timer relay 126. In making an exposure, the operator manually moves the arm 38 of the timer to a position indicating the time duration of the desired exposure in minutes indicated by the indicia 39.

The operator then closes the push button switch I22 energizing the timer. The relay K3 is energized through the energization of the timer and contacts 5 and 8 of the relay Kl. The pairs of contacts of relay K3 close, shorting out the capacitor C I so that the arc lamp 46 receives the full power from the secondary I20 of the transformer T1 for making an exposure. The motor B2 is energized through the timer and closed contacts 8 and 6 of the relay K2 rotating the blower 72 to direct a stream of air through the opening 76 in the reflector 48 into the region of the arc lamp 46 to cool the lamp to a nominal operating temperature.

Relay K4 is energized through the timer and through the closed contacts 1 and 3 of the relay K2. Energizing relay K4 opens the contacts 1 and 4 of relay K4 and closes the contacts l and 3 of relay K4. This action opens the dynamic braking circuit through the fields of the shutter operating motor 83 and energizes the drive motor B3 through the closed contacts 1 and 3 of relay K4 and the normally closed contacts of the limit switch S4 whereby the operation of the motor B3 opens the shutter 80.

When the shutter is opened, the drive motor B3 is deenergized and dynamic braking is applied through normally open contacts of switch S4, diodes CR3, CR4 and resistors R5 and R6 to the fields of the motor E3, the dynamic braking action preventing over-travel of the shutter at the terminus of its opening movement. At the expiration of the time interval for which the timer has been set, the relay K3 is de-energized and its contacts open, placing the capacitor C1 in series with the arc lamp 46, which action reduces the power supplied to the lamp 46, placing the lamp in a standby condition.

The blower motor B2 is de-energized and relay K4 is de-energized. Contacts 1 and 3 of relay K4 open deenergizing ,the dynamic braking circuit for the motor B3. Contacts 1 and 4 of the relay K4 close, energizing the drive motor B3 through the normally closed (N.C.) contactsiof the switch 53. This action energizes the motor B3 which closes the shutter. When the shutter is closed, the motor B3 is de-energized and dynamic braking applied to the motor B3 through normally open (N.O.) contacts of switch S3, diodes CR3, CR4 and resistors R5 and R6 to the fields of themotor preventing over-travel of the motor when the shutter has been moved to closed position.

This completes a cycleof operations in carrying on an exposure to completion and a closing of the shutter. The circuit and lamp are now in condition for a subsequent automatic operation in making an exposure simply by closing the switch 122.

During standby operation, the lamp 46 is operating under a low power condition at a warm up tempera ture, the motor B2 for driving the blower 72 is de energized, but the housing cooling fan 66 continues operation as the motor B1 for operating the ventilating fan 66 is energized as long as power is supplied to the transformer T1. In order to de-energize the gas dis' charge lamp 46 and the motor Bl driving the ventilating fan 66, it is only necessary to move the main switch S1 to open circuit position.

Through the arrangement above described, the secondary voltage of the single transformer T1 is summated with the peak voltage of the capacitor C] during the two half cycles of the alternating current frequency providing substantially double the voltage of the secondary 120 of the transformer so that a sufficiently high voltage is established at the lamp 46 to effect ionization and ignition of the gas discharge are lamp 46 without the necessity of using a special starting transformer or other devices which have heretofore been necessary in establishing the ignition of a gas discharge are lamp.

Furthermore, the arrangement of blower 72 provides for special cooling of the arc lamp 46 during high power operation of the lamp. the special cooling system for the lamp supplementing the continuously operating ventilating system for the lamp housing. The arrangement of the invention provides normal alternating current for the gas discharge lamp thus eliminating rectifier means heretofore used for powering a gas discharge are lamp after ignition has been established.

While two diodes CR1 and CR2 are illustrated for establishing, through the capacitor C], an increased voltage for igniting the are, it is tobe understood that a single diode or diode means of sufficient capacity may be utilized for the purpose.

Through the use of a single transformer for both lamp ignition and normal lamp operation, the energy efficiency of the system is improved over prior systems. The dynamic braking system for the shutter operating motor accomplishes several advantages. It avoids the liability of overtravel of the shutter when the shutter reaches open and closed positions. ln the dynamic braking system, the diodes CR3 and CR4 provide a direct current braking effect to all of the fields of the motor, a condition which enables the braking current to be applied and maintained to the motor fields except when the shutter is being moved from one position to the other. By applying braking current to all of the motor fields, a maximum braking effect is obtained, and as the current is apportioned among the several fields, the dynamic braking current may be continued without overheating the motor. With the shutter-operating motor B3 dynamically locked in either open or closed position of the shutter, there is no liability for the shutter to creep as the motor does not operate except through the time delay relay.

It is apparent that, within the scope of the invention, modifications and different arrangements may be made other than as herein disclosed, and the present disclosure is illustrative merely, the invention comprehending all variations thereof. i

We claim:

1. An illuminating system comprising a gas discharge lamp, a housing for said lamp, a circuit including a transformer connected witha supply of alternating current for the lamp, a circuit for the lamp including a capacitor in series with the secondary of the transformer and the gas discharge lamp for low power operation of the lamp a timer adapted to be adjusted to time the duration of high power operation of the lamp, relay means operable through the timer to short out the capacitor to establish high power operation of the lamp during the period for which the timer is adjusted, relatively movable shutter means comprising a sheet of flexible material associated with said housing, flexible cable means connected with the end regions of the sheet of flexible material, a motor having a drive roll engaging the cable means for actuating said sheet of material, said sheetbeing operable when in open position to pass light from the gas discharge lamp and in closed position to substantially impede the passage of light from the lamp, and second relay means energized through the timer to actuate the motor to move the sheet of material to open position, said second relay means being operable when the time period for high power operation of the lamp expires to connect the capacitor in series with the lamp for low power operation and to energize the drive motor to move the sheet of material to closed position,

2. An illuminating system comprising a gas discharge lamp, a housing for said lamp. a circuit including a transformer connected with a supply of alternating current for the lamp. a circuit for the lamp including a capacitor in series with the secondary of the transformer and the gas discharge lamp for low power operation of the lamp, a timer adapted to be adjusted to time the duration of high power operation of the lamp, relay means operable through the timer to short out the capacitor to establish high power operation of the lamp during the period for which the timer has been adjusted. relatively movable shutter means comprising a sheet of flexible material associated with said housing, flexible cable means connected with the end regions of the sheet of flexible material, a motor having a drive roll engaging the cable means for actuating said sheet of material, said sheet being operable when in open position to pass light from the gas discharge lamp and in closed position to substantially impede the passage of light from the lamp, relay means energized through the timer to actuate the motor to move the flexible sheet of material to open position, diode means and resistance means associated with the fields of the motor, switch means operable when the sheet of material is moved to open position for applying dynamic braking to said motor through the diode means and the resistance means to prevent over-travel of the sheet of material, second relay means operable when the time period for high power operation of the lamp expires to connect the capacitor in series with the lamp for low power operation and to energize the drive motor to move the sheet of material to closed position. and switch means operable upon closing of the sheet of material to de-energize the motor and apply dynamic braking to the fields of the motor through the diode means and resistance means to prevent over-travel of the sheet of material in closed position.

3. An illuminating system comprising a gas discharge lamp, a housing for the lamp, a circuit including a transformer connected with a supply of alternating current for the lamp, a circuit for the lamp including a capacitor in series with the secondary of the transformer and the gas discharge lamp, diode means, first relay means for connecting the diode means across the gas discharge lamp and in series with the capacitor across the secondary of the transformer whereby the capacitor is charged to peak voltage through the diode means during one-halfcycle. the peak voltage ofthe capacitor summatcd with the applied voltage from the secondary of the transformer during the alternate half cycle providing increased voltage applied to the gas discharge lamp sufficient to establish the arc in the gas discharge lamp, an adjustable timer for determining the duration of high power operation of the lamp, second relay means operable through the timer to establish high power operation of the lamp during the period for which the timer is adjusted, relatively movable shutter means comprising a sheet of flexible material associated with said housing operable when in open position to pass light from the lamp and in closed position to substantially impede the passage oflight from the lamp, a motor operable for moving the sheet of material to open and closed positions, and third relay means energized through the timer to actuate the motor to move the sheet of material to open position, said second relay means being operable when the time period for high power operation of the lamp expires to connect the capacitor in series with the lamp for low power operation, said third relay means being operable when the time period of the timer for high power operation of the lamp expires to energize the drive motor to move the sheet of material to closed position.

4. The system according to claim 3 including second diode means and resistance means associated with the fields of the motor, switch means operable when the sheet of material is moved to open position for applying dynamic braking to the motor through the second diode means and the resistance means to prevent overtravel of the sheet of material. and second switch means operable when the sheet of material is moved to closed position to de-energize the motor and apply dynamic braking to the fields of the motor through the second diode means and resistance means to prevent over-travel of the sheet of material in closed positionv i k 

1. An illuminating system comprising a gas discharge lamp, a housing for said lamp, a circuit including a transformer connected with a supply of alternating current for the lamp, a circuit for the lamp including a capacitor in series with the secondary of the transformer and the gas discharge lamp for low power operation of the lamp, a timer adapted to be adjusted to time the duration of high power operation of the lamp, relay means operable through the timer to short out the capacitor to establish high power operation of the lamp during the period for which the timer is adjusted, relatively movable shutter means comprising a sheet of flexible material associated with said housing, flexible cable means connected with the end regions of the sheet of flexible material, a motor having a drive roll engaging the cable means for actuating said sheet of material, said sheet being operable when in open position to pass light from the gas discharge lamp and in closed position to substantially impede the passage of light from the lamp, and second relay means energized through the timer to actuate the motor to move the sheet of material to open position, said second relay means being operable when the time period for high power operation of the lamp expires to connect the capacitor in series with the lamp for low power operation and to energize the drive motor to move the sheet of material to closed position.
 2. An illuminating system comprising a gas discharge lamp, a housing for said lamp, a circuit including a transformer connected with a supply of alternating current for the lamp, a circuit for the lamp including a capacitor in series with the secondary of the transformer and the gas discharge lamp for low power operation of the lamp, a timer adapted to be adjusted to time the duration of high power operation of the lamp, relay means operable through the timer to short out the capacitor to establish high power operation of the lamp during the period for which the timer has been adjusted, relatively movable shutter means comprising a sheet of flexible material associated with said housing, flexible cable means connected with the end regions of the sheet of flexible material, a motor having a drive roll engaging the cable means for actuating said sheet of material, said sheet being operable when in open position to pass light from the gas discharge lamp and in closed position to substantially impede the passage of light from the lamp, relay means energized through the timer to actuate the motor to move the flexible sheet of material to open position, diode means and resistance means associated with the fields of the motor, switch means operable when the sheet of material is moved to open position for applying dynamic braking to said motor through the diode means and the resistance means to prevent over-travel of the sheet of material, second relay means operable when the time period for high power operation of the lamp expires to connect the capacitor in series with the lamp for low power operation and to energize the drive motor to move the sheet of material to closed position, and switch means operable upon closing of the sheet of material to de-energize the motor and apply dynamic braking to the fields of the motor through the diode means and resistance means to prevent over-travel of the sheet of material in closed position.
 3. An illuminating system comprising a gas discharge lamp, a housing for the lamp, a circuit including a transformer connected with a supply of alternating current for the lamp, a circuit for the lamp including a capacitor in series with the secondary of the transformer and the gas discharge lamp, diode means, first relay means for connecting the diode means across the gas discharge lamp and in series with the capacitor across the secondary of the transformer whereby the capacitor is charged to peak voltage through the diode means during one-half cycle, the peak voltage of the capacitor summated with the applied voltage from the secondary of the transformer during the alternate half cycle providing increased voltage applied to the gas discharge lamp sufficient to establish the arc in the gas discharge lamp, an adjustable timer for determining the duration of high power operation of the lamp, second relay means operable through the timer to establish high power operation of the lamp during the period for which the timer is adjusted, relatively movable shutter means compRising a sheet of flexible material associated with said housing operable when in open position to pass light from the lamp and in closed position to substantially impede the passage of light from the lamp, a motor operable for moving the sheet of material to open and closed positions, and third relay means energized through the timer to actuate the motor to move the sheet of material to open position, said second relay means being operable when the time period for high power operation of the lamp expires to connect the capacitor in series with the lamp for low power operation, said third relay means being operable when the time period of the timer for high power operation of the lamp expires to energize the drive motor to move the sheet of material to closed position.
 4. The system according to claim 3 including second diode means and resistance means associated with the fields of the motor, switch means operable when the sheet of material is moved to open position for applying dynamic braking to the motor through the second diode means and the resistance means to prevent over-travel of the sheet of material, and second switch means operable when the sheet of material is moved to closed position to de-energize the motor and apply dynamic braking to the fields of the motor through the second diode means and resistance means to prevent over-travel of the sheet of material in closed position. 